Symptoms include tingling or numbness of the lips, prickliness of the fingertips and toes, nausea or vomiting, impaired balance, dizziness, slurred speech, double vision, weakness, difficulty in swallowing or breathing, loss of fluids and diarrhoea.

In severe cases PSP may cause muscular paralysis.

“It is important to note that cooking will not destroy these toxins,” Dr Lindsay said.

He said farmed shellfish purchased in supermarkets and other commercial outlets in WA are not affected.

“Other recreational activities including swimming, skiing and boating are not likely to be affected by this microalgae species, but as a general rule swimming should be avoided in areas of discoloured water,” he said.